US2667806A

US2667806A - Black body radiator and reflector

Info

Publication number: US2667806A
Application number: US229472A
Authority: US
Inventors: Joseph T Gier; Robert V Dunkle
Original assignee: University of California
Current assignee: University of California
Priority date: 1951-06-01
Filing date: 1951-06-01
Publication date: 1954-02-02
Anticipated expiration: 1971-02-02

Description

1954 J. T. GIER ET AL 2,667,806

BLACK BODY RADIATOR AND REFLECTOR Filed June 1, 1951 2 Sheets-Sheet 1 J. T. GIER ET AL BLACK BODY RADIATOR AND REFLECTOR Feb. 2, 1954 2 Sheets-Sheet 2 Filed June 1, 1951 INVEN TORS' Jail PH 6/51? 206597 Mam A4! HTTOAWVA'YJ Patented Feb. 2, 1954 UNITED STATES ATENT OFFICE BLACK BODY RADIATOR AND REFLECTOR Application June 1, 1951, Serial No. 229,472

3 Claims. 1

This invention relates to and in general has for its object the provision of a black bodyradiation generator and reflector, for determining the absolute spectral reflectivity of various materials when used in conjunction with a spectrometer.

More specifically, the object of this invention isthe provision'of adevice of the character above described including a uniformly heated chamber having an inner wall in which a water-cooled sample can be mounted, said chamber being provided with a small opening through which Planckian radiation respectively from the walls of the chamber or from the sample can pass for reflection to a spectrometer or other sensing device.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forth at length in the following description where that form of the invention which has been selected for illustration in the drawings accompanying and forming a part of the present specification is outlined in full. In said drawings, one form of the invention is shown, but it is to be understood that it is not limited to such form, since the invention asset forth in the claims may be embodied in a plurality offorms.

Referring'to the drawings:

Fig. 1 is a front elevation of a black body radiation generator and reflector embodying the objects of our invention.

Fig. 2 is a vertical mid-cross-section taken through the device illustrated in Fig. 1 but wherein the device has been rotated on its axis through 90 and tilted counter-clockwise and wherein an associated spectrometer system has been diagrammatically illustrated.

Fig. 3 is a View similar to Fig. 2 but wherein the device is tilted in a clockwise direction.

The device, as illustrated in these figures, includes a circular base I, formed with a central circular opening or window 2 and provided with opposed upstanding arms 3 and A. The upper ends of arms 3 and 4 are slotted as at 5 and serve as cradles or bearings for the reception respectively of coaxial trunnions 6 and 1, these trunnions being formed integral with a cylindrical steel shell 8. Disposed over the reduced ends of the trunnions 6 and l are washers 9 and threaded to the trunnions are wing nuts ll. As a result of this construction, the shell 8 can be locked in any desired angular position relative to the base I.

Fixed to and within the lower end of the shell 8 are a pair of insulating discs I2 and [3 toaxially therewith is an upwardly facing generally hemispherical cavity 2|, merging with a generally cylindrical cavity 22 machined from the upper cylinder 13 and having a substantially flat ceiling 33. Connected to the two ends of the re- Sistance element l9 are insulated leads 24 and 25 arranged to pass through an insulating grommet 23 mounted in the shell -8 and similarly connect-- ed to the ends of the resistance element 20 are insulated leads 21 and 28 arranged to pass through a grommet 29. Extending through the lower Wall of the lower cylinder I5 is an outwardly diverging conical opening 3! forming a continuation of theopening or window M'formed in the discs 12 and I3. Conveniently, the radii the height of theentire chamber and preferably the surfaceof the cavity 2! should pass through the midpoint of axis of the trunnions '6 and .l. A

cavity radius in the order of 1" having a diameter window in its lower wall has been found satisfactory.

Seated on top of the cylinder I6 and snugly fixed within the shell 8 are a pair of

insulating discs

32 and 33 formed with registering downwardly converging openings 34 and 35 for the reception of a slightly tapered porcelain tube 36 having a radial flange 31 at its upper end. The tube 36 extends through a hole 38 formed in the cylinder IS, the lower end of the tube being substantially flush with the ceiling 23. Filling the annular space between the shell 8 and copper cylinders l5 and I6 is a body 39 of comminuted insulating material such as diatomaceous earth.

Mounted within the porcelain tube 36 is a sample mounting assembly generally designated by the reference numeral 4|. This assembly comprises a bushing 42 having a lower end 43 of reduced diameter and receivable within the upper end of the porcelain tube 36. Mounted within and soldered to the lower end 43 is an elongated tube 44 extending just through the porcelain tube 33. Soldered to and across the lower end of the tube 44 is a disc 45 of the sample or material, the reflectivity of which is to be analyzed. Threaded Within the upper end of the bushing 42 is a plug r 3 46 provided with a central bore 41 and with offset bore 48. Mounted within the bore 41 is a water intake tube 49 extending to a point near the lower end of the tube 44. Secured to the lower end of the tube 49 is a bell 5| formed with a crenilated peripheral edge seated on the upper face of the sample disc 45. Fixed to and within the ofiset opening 48 is an elbow 52 serving as an outlet for the coolant which circulates downwardly through the tube 49, across the upper face of the sample 45 and then upwardly between the tubes 44 and 49 to the elbow.

From the above description it will be seen that we have provided a device comprising a Planckian or black-body radiator and reflector wherein a fluid-cooled sample of the material to be analyzed can be incorporated as a portion or continuation of the walls of the radiator.

As illustrated in Figs. 2 and 3, the above-clescribed device is used in a system including a focusing mirror subsystem generally designated by the reference numeral 53, a spectrometer 54, an intervening shield 55 and a recorder 56 operating under the influence of the spectrometer. Conveniently a so-called Perkin-Elmer infra-red recording spectrometer can be used for the spectrometer 54 and recorder 56.

The exposed area of the sample 45 in comparison to the surface of the heated cavity or chamber formed by the copper cylinders and i5 should be sufficiently small to make no appreciable change in the emission characteristics of the radiator. As illustrated in Figs. 2 and 3, the entire system is so arranged that by tilting the reilectometer shell 8 clockwise or counter-clockwise, energy emitted directly from the upper walls of the copper chamber or energy reflected from the sample 45 respectively can be directed into the spectrometer where it is detected (by the detector) as a function of wave length. Extraneous energy, energy from the environs, is minimized by appropriate shielding. The cooling system should serve to maintain the temperature of the sample surface approximately at the temperature of the radiation detector. When this condition prevails, the signal developed by the detector is indicative of the radiant energy emitted from the cavity walls or from the surface of the test specimen.

Having thus described our invention, what we claim and desire to secure by Letters Patent is:

1. A black body radiator and reflector comprising: a chamber having one wall thereof formed with a specimen receiving recess and an opposite wall thereof formed with a radiation emission window; means for heating said chamber thereby to generate Planckian radiation for reflection from a specimen disposed in said recess through said window; and a cooling system disposed in said recess for cooling a specimen mounted in said recess.

2. A black body radiator and reflector comprising: a chamber formed on one side thereof with a radiation emission window; a tube extending through a wall of said chamber at a point substantially opposite said window; a specimen mounted in the inner end of said tube with its inner surface substantially flush with the surrounding wall of said chamber; a cooling fluid conduit mounted within said tube, the inner end of said conduit terminating at a point substantially adjacent said specimen and means for heating said chamber thereby to generate Planckian radiation from the inner surfaces thereof, said radiation being reflectible from said specimen through said window.

3. A black body radiator and reflector comprising: a copper cylindrical chamber having a fiat upper wall and a concave lower wall, said upper wall being formed with a specimen receiving recess and said lower wall being provided with a radiation emission window; means for heating said chamber thereby to produce black body radiation for reflection through said window from a specimen disposed in said recess; and a cooling system disposed in said recess for cooling said specimen.

JOSEPH T. GIER. ROBERT V. DUNKLE.

References Cited in the file or" this patent UNITED STATES PATENTS Number Name Date 1,475,365 Schueler et a1 Nov. 27, 1923 2,110,748 Tweedale Mar. 8, 1938